After more than a decade of lobbying by lawmakers, a bill to legalize casino gambling is seen as having a decent chance of passing next year with the business-friendly Liberal Democratic Party in power and after Tokyo won the bid to host the Summer Olympics in 2020.

The three firms want to build a complex in Odaiba, near Tokyo Bay, that would include a hotel, conference center and a casino, Mitsui Fudosan said at an earnings briefing this week.

That plan hinges on the passage of the law and Tokyo being chosen to host a casino. Japan's biggest city is seen as a prime location for an integrated resort, but it is likely to face competition from more than a dozen other locations across the country.

"Our role in this project would be to get involved and make a contribution to help Tokyo become a more attractive city," said Masatoshi Satou, Mitsui Fudosan's executive managing officer. "But it is totally up to what happens to the bill and the direction of the government."

Mitsui Fudosan, Fuji Media and Kajima all declined to give further details on the project beyond saying that they had submitted a proposal to the government to develop a casino resort as part of a special economic zone.

Japan is widely viewed as one of the last great untapped markets due to its wealthy population and proximity to China. Union Gaming, a U.S.-based investment bank, has predicted Japanese gaming revenues could top $15 billion a year, making it the second-largest market in the world after Macau.

A group of more than 100 lawmakers, many from the LDP, will meet on Tuesday to finalize plans for an initial bill which they plan to submit during the current parliament session that ends next month.

If the legislation passes next year, as the lawmakers hope, the government would have to come up with concrete regulations within a year. That could mean the first casino would open in Japan in time for the 2020 Olympics.

Property developer Mori Building Co Ltd, which controls land in the Odaiba area, has also been working on plans to develop a casino resort with other companies, people with knowledge of the matter said.

A Mori Building spokesman said the company supports the move to legalize casinos and declined to comment further.